Publication Date:
2019-07-13
Description:
We present spectral and spatial information for major volatile species in Comet 10P/Tempel 2, based on high-dispersion infrared spectra acquired on UT 2010 July 26 (heliocentric distance Rh = 1.44 AU) and September 18 (Rh = 1.62 AU), following the comet's perihelion passage on UT 2010 July 04. The total production rate for water on July 26 was (1.90 +/- 0.12) x 10(exp 28) molecules per sec, and abundances of six trace gases (relative to water) were: CH3OH (1.58% +/- 0.23%), C2H6 (0.39% +/- 0.04%), NH3 (0.83% +/- 0.20%), and HCN (0.13% +/- 0.02%). A detailed analysis of intensities for water emission lines provided a rotational temperature of 35 +/- 3 K. The mean OPR is consistent with nuclear spin populations in statistical equilibrium (OPR = 3.01 +/- 0.18), and the (1(sigma)) lower bound corresponds to a spin temperature greater than 38 K. Our measurements were contemporaneous with a jet-like feature observed at optical wavelengths. The spatial profiles of four primary volatiles display strong enhancements in the jet direction, which favors release from a localized vent on the nucleus. The measured IR continuum is much more sharply peaked and is consistent with a dominant contribution from the nucleus itself. The peak intensities for H2O, CH3OH, and C2H6 are offset by approx. 200 km in the jet direction, suggesting the possible existence of a distributed source, such as the release of icy grains that subsequently sublimed in the coma. On UT September 18, no obvious emission lines were present in our spectra, nevertheless we obtained a 3(sigma) upper limit Q(H2O) less than 2.86 x 10(exp 27) molecules per sec.
Keywords:
Exobiology
Type:
GSFC-E-DAA-TN8865
,
Icarus (ISSN 0019-1035); 218; 1; 644-653
Format:
application/pdf
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